Recently an organic photoreceptor containing an organic photoconductive substance is widely used in an image forming apparatus according to an electrophotographic method. On the organic photoreceptor, various problems tend to be occurred on cleaning of the toner remained after transferring the toner to the image receiving material since the contact energy of the organic photoreceptor to the toner developing the latent image formed on the organic photoreceptor is large.
An electrophotographic image forming apparatus having a cleaning device just above a cylindrical electrophotographic photoreceptor has been proposed in Japanese Patent Application No. 11-290755. Such the image forming apparatus has an advantage that the apparatus can be made compact. When a blade scrapes the toner at the flank of the cylindrical photoreceptor, the toner is freely falls by the gravitation. However, when the cleaning blade is contacted just above to the photoreceptor, incompleteness of cleaning is often occurred since the toner scraped off by the cleaning blade tends to be remained on the surface of the photoreceptor.
Recently, a digital image forming method has been become as main stream of the image forming method accompanied with the progress of the digital technology. In the digital image forming method, a small dot image such as a image of 400 dpi is developed. Accordingly a high quality image forming technology is required by which such the small dot image can be reproduced with high fidelity.
One of the most important technologies for raising the image quality relates to the production of the toner. Currently, a toner produced by mixing, kneading, powdering and classifying a binder resin and a pigment has been mainly used for forming the electrophotographic image. However, the toner produced by such the process is insufficient in the particle size distribution and the shape uniformity. It is difficult to form an image with a sufficient quality by the use of such the toner.
A electrophotographic developer or an image forming method using a polymerized toner is proposed as the means for achieving the satisfactory particle size distribution and the uniform shape uniformity. The polymerized toner has the satisfactory particle size distribution and the shape uniformity since the toner is produced by polymerizing monomer uniformly dispersed in an aqueous medium.
A problem is newly raised when such the polymerized toner is used in an image forming apparatus having the organic photoreceptor. Namely, the cleaning tends to be incomplete since the shape of the toner particle is almost sphere and has a high attractive force to the organic photoreceptor surface.
Particularly, when the polymerized toner is applied to the image forming apparatus in which the cleaning device is arranged just above the cylindrical organic photoreceptor, very fine toner particles, by which no visible transferred image is formed, are slipped and passed through the cleaning blade and a charging device such as a charging wire or a charging roller is contaminated by such the very fine toner particles for a long period. As a result of the contamination, unevenness in the halftone image is formed.